PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov
Contacts: Mary A. Hardin/JPL
David Finley, National Radio Astronomy Observatory,
505/835-7302
FOR IMMEDIATE RELEASE
February 7, 1997
LAUNCH WILL CREATE A RADIO TELESCOPE LARGER THAN EARTH
NASA and the National Radio Astronomy Observatory are
joining with an international consortium of space agencies to
support the launch of a Japanese satellite next week that will
create the largest astronomical "instrument" ever built -- a
radio telescope more than two-and-a-half times the diameter of
the Earth that will give
astronomers their sharpest view yet of the universe.
The launch of the Very Long Base Interferometry (VLBI) Space
Observatory Program satellite by Japan's Institute of Space and
Astronautical Science (ISAS) is scheduled for February 10 at 8:50
p.m. Pacific time (1:50 p.m. February 11, Japan time.)
The satellite is part of an international collaboration led
by ISAS and backed by Japan's National Astronomical Observatory;
NASA's Jet Propulsion Laboratory (JPL); the National Science
Foundation's National Radio Astronomy Observatory (NRAO),
Socorro, NM; the Canadian Space Agency; the Australia Telescope
National Facility; the European VLBI Network and the Joint
Institute for Very Long Baseline Interferometry in Europe.
Very long baseline interferometry is a technique used by
radio astronomers to electronically link widely-separated radio
telescopes together so they work as if they were a single
instrument with extraordinarily sharp "vision," or resolving
power. The wider the distance between telescopes, the greater the
resolving power. By taking this technique into space for the
first time, astronomers will approximately triple the resolving
power previously available with only ground-based telescopes. The
satellite system will have resolving power almost 1,000 times
greater than the Hubble Space Telescope has at optical
wavelengths. The satellite's resolving power is equivalent to
being able to see a grain of rice in Tokyo from Los Angeles.
"Using space VLBI, we can probe the cores of quasars and
active galaxies, believed to be powered by super-massive black
holes," said Dr. Robert Preston, project scientist for the U.S.
Space Very Long Baseline Interferometry project at JPL.
"Observations of cosmic masers -- naturally-occurring microwave
radio amplifiers -- will tell us new things about the process of
star formation and activity in the heart of
other galaxies."
"By the 1980s, radio astronomers were observing the universe
with assemblages of radio telescopes whose resolving power was
limited only by the size of the Earth. Now, through a magnificent
international effort, we will be able to break this barrier and
see fine details of celestial objects that are beyond the reach
of a purely ground-based telescope array. We anticipate a rich
harvest of new scientific knowledge from VSOP," Dr. Paul Vanden
Bout, director of NRAO.
In the first weeks after launch, scientists and engineers
will "test the deployment of the reflecting mesh telescope in
orbit, the wide-band data link from the satellite to the ground,
the performance of the low noise amplifiers in orbit, and the
high-precision orbit determination and attitude control necessary
for VLBI observations with an orbiting telescope," according to
Dr. Joel Smith, manager of the U.S. Space Very Long Baseline
Interferometry project at JPL. Scientific observations are
expected to begin in May.
The 8-meter (26-foot) diameter orbiting radio telescope will
observe celestial radio sources in concert with a number of the
world's ground-based radio telescopes. The 830-kilogram (1,830-
pound) satellite will be launched from ISAS's Kagoshima Space
Center, at the southern tip of Kyushu, one of Japan's main
islands, and will be the first launch with ISAS's new M-5 series
rocket.
The satellite will go into an elliptical orbit, varying
between 1,000 and 20,000 kilometers (620 to 12,400 miles) above
the Earth's surface. This orbit provides a wide range of
distances between the satellite and ground-based telescopes,
which is important for producing a high-quality image of the
radio source being observed. One orbit of the
Earth will take about six hours.
The satellite's observations will concentrate on some of the
most distant and intriguing objects in the universe, where the
extremely sharp radio "vision" of the new system can provide
much-needed information about a number of astronomical mysteries.
For years, astronomers have known that powerful "engines" in
the hearts of quasars and many galaxies are pouring out
tremendous amounts of energy. They suspect that supermassive
black holes, with gravitational fields so strong that not even
light can escape them, lie in the centers of these "engines."
However, the mechanism at work in the centers of quasars and
active galaxies remains a mystery. Ground-based radio telescopes,
notably NRAO's Very Long Baseline Array (VLBA), have revealed
fascinating new details in recent years, and VSOP is expected to
add a wealth of new information on these objects, millions or
billions of light-years distant from Earth.
Many of these same objects act as super-powerful particle
accelerators to eject "jets" of subatomic particles at nearly the
speed of light. Scientists plan to use VSOP to monitor the
changes and motions in these jets to learn more about how they
originate and interact with their surroundings.
The satellite also will aim at regions in the sky where
giant collections of water and other molecules act as natural
amplifiers of radio emission much as lasers amplify light. These
regions, called cosmic masers, are found in regions where new
stars are forming and near the centers of galaxies. Observations
can provide the detail needed to measure motions of individual
maser "spots" within these regions, and provide exciting new
information about the star-forming regions and the galaxies
where the masers reside. In addition, high-resolution studies of
cosmic masers can allow astronomers to calculate
distances to them with unprecedented accuracy, and thus help
resolve continuing questions about the size and age of the
universe.
The project is a major international undertaking, with about
40 radio telescopes from more than 15 countries having committed
time to co-observe with the satellite. This includes the National
Science Foundation's Very Long Baseline Array (VLBA), an array of
10 telescopes spanning the United States from Hawaii to Saint
Croix; NASA's Deep Space Network sites in California, Spain, and
Australia; the European VLBI Network, more than a dozen
telescopes ranging from the United Kingdom to China; a Southern
Hemisphere array of telescopes stretching from eastern Australia
to South Africa; and Japan's network of domestic radio
telescopes.
In the United States, NASA is funding critical roles in the
VSOP mission at both JPL and NRAO. JPL has built an array of
three new tracking stations at its DSN sites in Goldstone,
California; Madrid, Spain; and near Canberra, Australia. A large
existing tracking station at each of these sites has also been
converted to an extremely sensitive radio telescope for
simultaneous observations with the satellite. JPL also is
providing precision orbit determination, scientific and
operational planning support to the Japanese, and advice to U.S.
astronomers who wish to observe with the satellite. NRAO is
building a new tracking station at Green Bank, West Virginia;
contributing observing time on the VLBA array of telescopes;
modifying existing data analysis hardware and software, and
aiding astronomers with the analysis of the VSOP data. Much of
the observational data will be processed at NRAO's facility in
Socorro, NM, using the VLBA Correlator, a special-purpose high-
performance computer designed to process VLBI data.
VSOP is the culmination of many years of planning and work
by scientists and engineers around the world. Tests using NASA's
Tracking and Data Relay Satellite System (TDRSS) proved the
feasibility of space VLBI in 1986. Just last year, those old data
were used again to successfully test the data-reduction
facilities for VSOP.
JPL manages the U.S. Space Very Long Baseline Interferometry
project for NASA's Office of Space Science, Washington, D.C. The
VLBA, headquartered in Socorro, New Mexico, is part of the
National Radio Astronomy Observatory, a facility of the National
Science Foundation, operated under cooperative agreement by
Associated Universities, Inc.
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